How to use specified weights for fonts in XML

Using the Fonts in XML feature you can specify various font weights for a font family. For example:

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:app="http://schemas.android.com/apk/res-auto">

    <font android:font="@font/archivo_narrow_regular" android:fontWeight="400" android:fontStyle="normal"
        app:font="@font/archivo_narrow_regular" app:fontWeight="400" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_regular_italic" android:fontWeight="400" android:fontStyle="italic"
        app:font="@font/archivo_narrow_regular_italic" app:fontWeight="400" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_medium" android:fontWeight="500" android:fontStyle="normal"
        app:font="@font/archivo_narrow_medium" app:fontWeight="500" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_medium_italic" android:fontWeight="500" android:fontStyle="italic"
        app:font="@font/archivo_narrow_medium_italic" app:fontWeight="500" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_semibold" android:fontWeight="600" android:fontStyle="normal"
        app:font="@font/archivo_narrow_semibold" app:fontWeight="600" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_semibold_italic" android:fontWeight="600" android:fontStyle="italic"
        app:font="@font/archivo_narrow_semibold_italic" app:fontWeight="600" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_bold" android:fontWeight="700" android:fontStyle="normal"
        app:font="@font/archivo_narrow_bold" app:fontWeight="700" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_bold_italic" android:fontWeight="700" android:fontStyle="italic"
        app:font="@font/archivo_narrow_bold_italic" app:fontWeight="700" app:fontStyle="italic"/>

</font-family>

But I cannot figure out how to actually make use of each of these weights; either in an XML (layout/style) file, or in Java code. Their is no fontWeight attribute available for TextView, and the Typeface object created from ResourcesCompat.getFont(context, R.font.archivo_narrow) has no mention of font weights.

I realize that I can just specify the specific font resource (i.e. R.font.archivo_narrow_semibold), but then what is the point of having a fontWeight attribute in the font-family?

Update

A new static create(Typeface family, int weight, boolean italic) method was added in API Level 28, along with a getWeight() instance method. This finally makes it possible to make use of the fontWeight attribute in Java code; though only for API Level 28 and above, I haven't found any analogs in the support library.

This is useful—and shows that the fontWeight attribute didn't serve any purpose in the past—but I would really like to be able to use the weight in XML styling.

As pointed out by @FlorianWalther, the TextView.textFontWeight attribute is exactly what I was looking for. This attribute was apparently added in API level 28, but was not documented until recently.

Make sure all of the weights are in the same XML file (as in my question), then simply use the attribute along with the fontFamily attribute.

<TextView android:id="@+id/weightedTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:fontFamily="@font/archivo_narrow"
    android:textFontWeight="700"/>

As far as I am aware this attribute is only available in API Level 28 an above, I will update if I find its counterpart in the support library.